PALO VERDE - Officials at a nuclear power plant here are trying to figure out how to remove highly radioactive fuel rods that became stuck without risking the release of deadly radioactive gas.

Officials at the Palo Verde Nuclear Generating Station and the Nuclear Regulatory Commission disclosed the problems only after being questioned by the Arizona Republic, the newspaper reported yesterday.

No radiation has been released since the problems began March 22 at the Palo Verde plant, the nation's largest nuclear power plant, officials told the Republic.

''What we're doing right now is being very cautious and careful,'' said Jack Bailey, the plant's vice president of nuclear engineering.

Bailey and other officials said there is no chance that massive radiation would be released into the environment.

Any radioactive gas released from a ruptured fuel rod would be captured by a containment building, and workers would be evacuated, they said.

Officials are worried that in trying to dislodge the 1,500-pound fuel assembly, they may damage one or more of the 236 fuel rods, the Republic reported. That would release radioactive iodine, krypton and xenon gas into a containment building and drop highly radioactive spent uranium fuel pellets into the bottom of the reactor core.

Even in a worst-case scenario of the problem, there would be no possibility of a nuclear meltdown or any release of nuclear radiation outside the containment building, said plant spokesman Jim McDonald.

Damaging a fuel rod, however, would prompt a costly cleanup and incalculable delay in restarting the reactor. Consumers would end up with increased energy costs, officials said.

Palo Verde officials first noticed a problem on March 22 when one of 241 fuel bundles in the reactor core could not be lifted out during a routine refueling operation.

After the rest of the fuel assemblies were removed from the reactor, a remote-control hydraulic jack lifted the problem fuel bundle slightly. But officials are concerned about excessive pressure on the bundle.

Officials believe that a damaged cap, part of a 100,000-pound device used to set the bundle in place, caused the problem during a refueling last year by driving the bottom of the fuel assembly lower than intended.

It is the first time a fuel assembly has become stuck at any of the three units at Palo Verde, which began operating a decade ago in the desert 50 miles west of downtown Phoenix.

Breck Henderson, a spokesman for the regional office of the NRC in Arlington, Texas, said NRC inspectors were sent to the plant to help monitor the situation.

The Texas office of NRC is in charge of 21 reactors at 14 sites in the West.

Bailey said Palo Verde officials will continue inspecting the assembly core and develop a strategy for its removal.